The present invention relates to crop harvesting machines and more particularly relates to a modular cutterbar for a rotary mower.
Typically, rotary mower cutterbars include a fluid tight gear housing which contains a gear train for driving cutting units spaced along the length of the cutterbar. These cutterbars are usually driven from below. Consequently, it is desirable to keep the vertical space required for the drive train to a minimum in order for the cutterbar to be operated for disposing the cutting units in close proximity to the ground so as to result in a low height of cut. The gear train which best accomplishes this desired result is one made up of a plurality of spur gears.
U.S. Pat. No. 4,468,916, granted to Vissers et al on Sept. 4, 1984, discloses a cutterbar structure made up of a plurality of like intermediate gear housing sections that are bolted together in end-to-end relationship with one another and of right and left end gear housing sections which are respectively coupled to the right and left ends respectively of the assembled intermediate sections. The patent discloses a first embodiment of the gear housing sections wherein an integral portion of one end of each of the end sections and of the opposite ends of each the intermediate sections is defined by semi-cylindrical surfaces adapted for receiving a pair of bearings for rotatably supporting a cutting unit drive shaft, the latter having a pinion gear formed on the lower end thereof. Located in each of the intermediate sections on the centerline passing through the semi-cylindrical end surfaces are a pair of idler shaft mounting structures defined by first and second sets of upper and lower axially aligned holes respectively located in top and bottom walls of the sections. An idler gear mounting shaft is pressed into each set of axially aligned holes and rotatably mounted on each shaft by means of a respective bearing is an idler gear. Thus, when a plurality of the sections are assembled together for forming a cutterbar, the pinion and idler gears are in series and operate such that adjacent pairs of the cutting units will rotate in opposite directions.
This patented cutterbar has the disadvantages that:
1. Only cutterbars having an even number of cutting units can be assembled thus limiting the possible lengths of cutterbars which can be made.
2. The one end face of each of the right and left hand gear housing sections and the two end faces of each of the intermediate sections are relatively complex.
3. The end gear housing sections are of a different construction than the intermediate sections which results in an increase in the cost of the manufacture of the cutterbars.
4. Servicing or replacement of the bearings associated with the cutting unit drive shaft requires the cutterbar to be disassembled to retrieve the failed part which is not desirable since such disassembly would require that the gear lubricant first be drained from the cutterbar; and such disassembly might require that a hoist or like machinery be employed to handle relatively heavy assemblages of housing sections and gears.
5. The assembly of the cutterbar is complicated by the fact that the drive shaft and associated bearings must be mounted in place during the securing together of adjacent gear housing sections and that fixtures must be provided to hold one section in place while another is assembled to it.